Panic exit devices of the type to which the invention relates commonly incorporate a push plate or bar, spanning the full width or portion of the width of the doorway which is pushed to unlatch and swing the door open.
By their name, the devices are typically used on doors of emergency exits, such as fire doors, or doors which are used to allow the passage of large crowds, such as in a gymnasium. The dependable and reliable operation of these devices is obviously crucial.
When the panic exit devices are provided to allow for the passage of a substantial number of people at one time, such as a gymnasium or arena door, it is advantageous to secure the device in the unlatched position, i.e., dogged. Dogging the door minimizes wear on the latching mechanism while also allowing for the door to immediately swing open upon pushing by an exiting person.
Because in installations where dogging is most desirable many panic exit doors are used, an efficient and simple method of dogging is demanded. Manually dogging of each panic exit door, although feasible, takes time. Typically, prior art manual dogging mechanisms required personnel to manually retract each door latch individually by pushing the push bar inward and then engaging the dogging mechanism. An example of such a mechanism is shown in Zawadzki, U.S. Pat. No. 3,730,574. In addition, any time spent by maintenance personnel manually dogging the doors also required at least equal time by maintenance personnel to undog them.
As a result, electrical latch control, including electrical dogging, is desirable. Namely, it can be done from a remote location, in minimal time and using minimal personnel. Such electric dogging devices are shown in Zawadzki, U.S. Pat. Nos. 3,854,763 and 3,767,238. These devices, however, require relatively complicated operating mechanisms. Moreover, it is desirable that dogging through an electric latch control device could be adapted to be used with any door latch mechanism, e.g. a rim latch or vertical rod latch. Finally, it is further desirable if a manual dogging capability could also be featured.